Battery pack

Abstract

A battery pack includes a series of battery cells, a series of bus bars electrically connecting the series of battery cells, and a terminal member. The terminal member includes a first metal layer extending from an internal connection position connected to at least one of the series of bus bars to an external connection position for supplying output power of the battery pack. The terminal member also includes a second metal layer covering the first metal layer at the external connection position. The second metal layer includes a second metal different from a first metal of the first metal layer. Therefore, the battery pack has an improved structure for stable and low-resistance connection.

What is claimed is: 
     
       1. A battery pack comprising:
 a plurality of battery cells; 
 a plurality of bus bars electrically connecting the plurality of battery cells; and 
 a terminal member, 
 wherein the terminal member comprises: 
 a first metal layer extending from an internal connection position connected to at least one of the plurality of bus bars to an external connection position for supplying output power of the battery pack, the external connection position being outside of and extending beyond the plurality of battery cells; and 
 a second metal layer covering the first metal layer at the external connection position, the second metal layer comprising a second metal different from a first metal of the first metal layer. 
 
     
     
       2. The battery pack of  claim 1 , further comprising:
 a bolt member configured to penetrate the second metal layer at the external connection position; and 
 a nut member protruding from an insulative support surface, wherein the bolt member is configured to be fastened to the nut member. 
 
     
     
       3. The battery pack of  claim 2 , wherein:
 the first and second metal layers overlap each other at the external connection position, 
 the first metal layer extends around an outer periphery of the nut member, and 
 the second metal layer is on an upper surface of the nut member. 
 
     
     
       4. The battery pack of  claim 3 , wherein the first metal layer includes a first hole which is larger than the outer periphery of the nut member, and wherein the nut member extends through the first hole. 
     
     
       5. The battery pack of  claim 4 , wherein the second metal layer includes a second hole which is smaller than the outer periphery of the nut member, and wherein the second metal layer is supported on the upper surface of the nut member along a periphery of the second hole. 
     
     
       6. The battery pack of  claim 5 , wherein the first and second holes are at the external connection position, and wherein the first and second holes have concentric circular shapes having an identical center and different diameters. 
     
     
       7. The battery pack of  claim 5 , wherein the bolt member is fastened to the nut member through the second hole. 
     
     
       8. The battery pack of  claim 2 ,
 wherein the first metal layer is between the insulative support surface from which the nut member protrudes and the second metal layer on an upper surface of the nut member. 
 
     
     
       9. The battery pack of  claim 8 , wherein the first metal layer and a portion of the nut member protruding from the insulative support surface are adjacent to each other between the insulative support surface and the second metal layer. 
     
     
       10. The battery pack of  claim 1 , wherein the first metal layer comprises a first metal and the second metal layer comprises a second metal different than the first metal. 
     
     
       11. The battery pack of  claim 10 , wherein the second metal layer has a mechanical rigidity greater than a mechanical rigidity of the first metal layer. 
     
     
       12. The battery pack of  claim 11 , wherein the first metal comprises aluminum, and the second metal comprises copper. 
     
     
       13. The battery pack of  claim 1 , wherein the terminal member further comprises a conductive bonding layer forming a conductive bond between the first and second metal layers. 
     
     
       14. The battery pack of  claim 13 , wherein the conductive bonding layer comprises at least one of solder paste, a conductive film, or a conductive adhesive. 
     
     
       15. The battery pack of  claim 1 , further comprising a first plating layer on a first surface of the first metal layer facing the second metal layer, and a second plating layer on a second surface of the second metal layer facing the first surface of the first metal layer. 
     
     
       16. The battery pack of  claim 15 , further comprising a third plating layer on the second plating layer. 
     
     
       17. The battery pack of  claim 16 , wherein the first and second plating layers each comprise nickel, and the third plating layer comprises tin. 
     
     
       18. The battery pack of  claim 2 ,
 wherein, in a state in which the bolt member and the nut member are not fastened to each other, the nut member protrudes from the insulative support surface to a first height, and the first metal layer has a thickness less than the first height and is spaced apart from the insulative support surface. 
 
     
     
       19. The battery pack of  claim 18 , wherein a clearance gap is between the first metal layer and the insulative support surface. 
     
     
       20. The battery pack of  claim 18 , wherein, in a state in which the bolt member and the nut member are fastened to each other, the nut member protrudes from the insulative support surface to a second height, and the first metal layer is in contact with the insulative support surface. 
     
     
       21. The battery pack of  claim 20 , wherein the second height is lower than the first height. 
     
     
       22. The battery pack of  claim 2 ,
 wherein the second metal layer is between a head of the bolt member and the nut member, and wherein the first metal layer is spaced away from a gap between the head of the bolt member and the nut member. 
 
     
     
       23. The battery pack of  claim 22 , wherein, in a state in which the bolt member and the nut member are fastened to each other, the head of the bolt member has an area covering both the nut member and a portion of the first metal layer around the nut member.